--- ray/src/rt/aniso.c	1993/02/12 10:41:05	2.23
+++ ray/src/rt/aniso.c	2003/03/12 04:59:05	2.38
@@ -1,13 +1,12 @@
-/* Copyright (c) 1992 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char RCSid[] = "$Id: aniso.c,v 2.38 2003/03/12 04:59:05 greg Exp $";
 #endif
-
 /*
  *  Shading functions for anisotropic materials.
  */
 
+#include "copyright.h"
+
 #include  "ray.h"
 
 #include  "otypes.h"
@@ -16,8 +15,9 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #include  "random.h"
 
-extern double  specthresh;		/* specular sampling threshold */
-extern double  specjitter;		/* specular sampling jitter */
+#ifndef  MAXITER
+#define  MAXITER	10		/* maximum # specular ray attempts */
+#endif
 
 /*
  *	This routine implements the anisotropic Gaussian
@@ -34,8 +34,6 @@ extern double  specjitter;		/* specular sampling jitte
  *  8  red 	grn	blu	rspec	u-rough	v-rough	trans	tspec
  */
 
-#define  BSPEC(m)	(6.0)		/* specularity parameter b */
-
 				/* specularity flags */
 #define  SP_REFL	01		/* has reflected specular component */
 #define  SP_TRAN	02		/* has transmitted specular */
@@ -62,7 +60,11 @@ typedef struct {
 	double  pdot;		/* perturbed dot product */
 }  ANISODAT;		/* anisotropic material data */
 
+static void	getacoords();
+static void	agaussamp();
 
+
+static void
 diraniso(cval, np, ldir, omega)		/* compute source contribution */
 COLOR  cval;			/* returned coefficient */
 register ANISODAT  *np;		/* material data */
@@ -176,23 +178,33 @@ double  omega;			/* light source size */
 }
 
 
+int
 m_aniso(m, r)			/* shade ray that hit something anisotropic */
 register OBJREC  *m;
 register RAY  *r;
 {
 	ANISODAT  nd;
-	double  dtmp;
 	COLOR  ctmp;
 	register int  i;
 						/* easy shadow test */
 	if (r->crtype & SHADOW)
-		return;
+		return(1);
 
 	if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6))
 		objerror(m, USER, "bad number of real arguments");
+						/* check for back side */
+	if (r->rod < 0.0) {
+		if (!backvis && m->otype != MAT_TRANS2) {
+			raytrans(r);
+			return(1);
+		}
+		raytexture(r, m->omod);
+		flipsurface(r);			/* reorient if backvis */
+	} else
+		raytexture(r, m->omod);
+						/* get material color */
 	nd.mp = m;
 	nd.rp = r;
-						/* get material color */
 	setcolor(nd.mcolor, m->oargs.farg[0],
 			   m->oargs.farg[1],
 			   m->oargs.farg[2]);
@@ -202,11 +214,7 @@ register RAY  *r;
 	nd.v_alpha = m->oargs.farg[5];
 	if (nd.u_alpha < FTINY || nd.v_alpha <= FTINY)
 		objerror(m, USER, "roughness too small");
-						/* reorient if necessary */
-	if (r->rod < 0.0)
-		flipsurface(r);
-						/* get modifiers */
-	raytexture(r, m->omod);
+
 	nd.pdot = raynormal(nd.pnorm, r);	/* perturb normal */
 	if (nd.pdot < .001)
 		nd.pdot = .001;			/* non-zero for diraniso() */
@@ -220,15 +228,8 @@ register RAY  *r;
 		else
 			setcolor(nd.scolor, 1.0, 1.0, 1.0);
 		scalecolor(nd.scolor, nd.rspec);
-						/* improved model */
-		dtmp = exp(-BSPEC(m)*nd.pdot);
-		for (i = 0; i < 3; i++)
-			colval(nd.scolor,i) += (1.0-colval(nd.scolor,i))*dtmp;
-		nd.rspec += (1.0-nd.rspec)*dtmp;
 						/* check threshold */
-		if (specthresh > FTINY &&
-				(specthresh >= 1.-FTINY ||
-				specthresh + .05 - .1*frandom() > nd.rspec))
+		if (specthresh >= nd.rspec-FTINY)
 			nd.specfl |= SP_RBLT;
 						/* compute refl. direction */
 		for (i = 0; i < 3; i++)
@@ -245,9 +246,7 @@ register RAY  *r;
 		if (nd.tspec > FTINY) {
 			nd.specfl |= SP_TRAN;
 							/* check threshold */
-			if (specthresh > FTINY &&
-					(specthresh >= 1.-FTINY ||
-				specthresh + .05 - .1*frandom() > nd.tspec))
+			if (specthresh >= nd.tspec-FTINY)
 				nd.specfl |= SP_TBLT;
 			if (DOT(r->pert,r->pert) <= FTINY*FTINY) {
 				VCOPY(nd.prdir, r->rdir);
@@ -266,8 +265,8 @@ register RAY  *r;
 						/* diffuse reflection */
 	nd.rdiff = 1.0 - nd.trans - nd.rspec;
 
-	if (r->ro != NULL && (r->ro->otype == OBJ_FACE ||
-			r->ro->otype == OBJ_RING))
+	if (r->ro != NULL && isflat(r->ro->otype) &&
+			DOT(r->pert,r->pert) <= FTINY*FTINY)
 		nd.specfl |= SP_FLAT;
 
 	getacoords(r, &nd);			/* set up coordinates */
@@ -276,7 +275,7 @@ register RAY  *r;
 		agaussamp(r, &nd);
 
 	if (nd.rdiff > FTINY) {		/* ambient from this side */
-		ambient(ctmp, r);
+		ambient(ctmp, r, nd.pnorm);
 		if (nd.specfl & SP_RBLT)
 			scalecolor(ctmp, 1.0-nd.trans);
 		else
@@ -285,8 +284,13 @@ register RAY  *r;
 		addcolor(r->rcol, ctmp);	/* add to returned color */
 	}
 	if (nd.tdiff > FTINY) {		/* ambient from other side */
+		FVECT  bnorm;
+
 		flipsurface(r);
-		ambient(ctmp, r);
+		bnorm[0] = -nd.pnorm[0];
+		bnorm[1] = -nd.pnorm[1];
+		bnorm[2] = -nd.pnorm[2];
+		ambient(ctmp, r, bnorm);
 		if (nd.specfl & SP_TBLT)
 			scalecolor(ctmp, nd.trans);
 		else
@@ -297,10 +301,12 @@ register RAY  *r;
 	}
 					/* add direct component */
 	direct(r, diraniso, &nd);
+
+	return(1);
 }
 
 
-static
+static void
 getacoords(r, np)		/* set up coordinate system */
 RAY  *r;
 register ANISODAT  *np;
@@ -313,7 +319,7 @@ register ANISODAT  *np;
 	errno = 0;
 	for (i = 0; i < 3; i++)
 		np->u[i] = evalue(mf->ep[i]);
-	if (errno) {
+	if (errno == EDOM || errno == ERANGE) {
 		objerror(np->mp, WARNING, "compute error");
 		np->specfl |= SP_BADU;
 		return;
@@ -330,7 +336,7 @@ register ANISODAT  *np;
 }
 
 
-static
+static void
 agaussamp(r, np)		/* sample anisotropic gaussian specular */
 RAY  *r;
 register ANISODAT  *np;
@@ -339,69 +345,81 @@ register ANISODAT  *np;
 	FVECT  h;
 	double  rv[2];
 	double  d, sinp, cosp;
+	int  niter;
 	register int  i;
 					/* compute reflection */
 	if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL &&
 			rayorigin(&sr, r, SPECULAR, np->rspec) == 0) {
 		dimlist[ndims++] = (int)np->mp;
-		d = urand(ilhash(dimlist,ndims)+samplendx);
-		multisamp(rv, 2, d);
-		d = 2.0*PI * rv[0];
-		cosp = cos(d) * np->u_alpha;
-		sinp = sin(d) * np->v_alpha;
-		d = sqrt(cosp*cosp + sinp*sinp);
-		cosp /= d;
-		sinp /= d;
-		rv[1] = 1.0 - specjitter*rv[1];
-		if (rv[1] <= FTINY)
-			d = 1.0;
-		else
-			d = sqrt(-log(rv[1]) /
-				(cosp*cosp/(np->u_alpha*np->u_alpha) +
-				 sinp*sinp/(np->v_alpha*np->v_alpha)));
-		for (i = 0; i < 3; i++)
-			h[i] = np->pnorm[i] +
-				d*(cosp*np->u[i] + sinp*np->v[i]);
-		d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d);
-		for (i = 0; i < 3; i++)
-			sr.rdir[i] = r->rdir[i] + d*h[i];
-		if (DOT(sr.rdir, r->ron) <= FTINY)	/* penetration? */
-			VCOPY(sr.rdir, np->vrefl);	/* jitter no good */
-		rayvalue(&sr);
-		multcolor(sr.rcol, np->scolor);
-		addcolor(r->rcol, sr.rcol);
+		for (niter = 0; niter < MAXITER; niter++) {
+			if (niter)
+				d = frandom();
+			else
+				d = urand(ilhash(dimlist,ndims)+samplendx);
+			multisamp(rv, 2, d);
+			d = 2.0*PI * rv[0];
+			cosp = tcos(d) * np->u_alpha;
+			sinp = tsin(d) * np->v_alpha;
+			d = sqrt(cosp*cosp + sinp*sinp);
+			cosp /= d;
+			sinp /= d;
+			rv[1] = 1.0 - specjitter*rv[1];
+			if (rv[1] <= FTINY)
+				d = 1.0;
+			else
+				d = sqrt(-log(rv[1]) /
+					(cosp*cosp/(np->u_alpha*np->u_alpha) +
+					 sinp*sinp/(np->v_alpha*np->v_alpha)));
+			for (i = 0; i < 3; i++)
+				h[i] = np->pnorm[i] +
+					d*(cosp*np->u[i] + sinp*np->v[i]);
+			d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d);
+			for (i = 0; i < 3; i++)
+				sr.rdir[i] = r->rdir[i] + d*h[i];
+			if (DOT(sr.rdir, r->ron) > FTINY) {
+				rayvalue(&sr);
+				multcolor(sr.rcol, np->scolor);
+				addcolor(r->rcol, sr.rcol);
+				break;
+			}
+		}
 		ndims--;
 	}
 					/* compute transmission */
 	if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN &&
 			rayorigin(&sr, r, SPECULAR, np->tspec) == 0) {
 		dimlist[ndims++] = (int)np->mp;
-		d = urand(ilhash(dimlist,ndims)+1823+samplendx);
-		multisamp(rv, 2, d);
-		d = 2.0*PI * rv[0];
-		cosp = cos(d) * np->u_alpha;
-		sinp = sin(d) * np->v_alpha;
-		d = sqrt(cosp*cosp + sinp*sinp);
-		cosp /= d;
-		sinp /= d;
-		rv[1] = 1.0 - specjitter*rv[1];
-		if (rv[1] <= FTINY)
-			d = 1.0;
-		else
-			d = sqrt(-log(rv[1]) /
-				(cosp*cosp/(np->u_alpha*np->u_alpha) +
-				 sinp*sinp/(np->v_alpha*np->u_alpha)));
-		for (i = 0; i < 3; i++)
-			sr.rdir[i] = np->prdir[i] +
-					d*(cosp*np->u[i] + sinp*np->v[i]);
-		if (DOT(sr.rdir, r->ron) < -FTINY)
-			normalize(sr.rdir);		/* OK, normalize */
-		else
-			VCOPY(sr.rdir, np->prdir);	/* else no jitter */
-		rayvalue(&sr);
-		scalecolor(sr.rcol, np->tspec);
-		multcolor(sr.rcol, np->mcolor);		/* modify by color */
-		addcolor(r->rcol, sr.rcol);
+		for (niter = 0; niter < MAXITER; niter++) {
+			if (niter)
+				d = frandom();
+			else
+				d = urand(ilhash(dimlist,ndims)+1823+samplendx);
+			multisamp(rv, 2, d);
+			d = 2.0*PI * rv[0];
+			cosp = tcos(d) * np->u_alpha;
+			sinp = tsin(d) * np->v_alpha;
+			d = sqrt(cosp*cosp + sinp*sinp);
+			cosp /= d;
+			sinp /= d;
+			rv[1] = 1.0 - specjitter*rv[1];
+			if (rv[1] <= FTINY)
+				d = 1.0;
+			else
+				d = sqrt(-log(rv[1]) /
+					(cosp*cosp/(np->u_alpha*np->u_alpha) +
+					 sinp*sinp/(np->v_alpha*np->v_alpha)));
+			for (i = 0; i < 3; i++)
+				sr.rdir[i] = np->prdir[i] +
+						d*(cosp*np->u[i] + sinp*np->v[i]);
+			if (DOT(sr.rdir, r->ron) < -FTINY) {
+				normalize(sr.rdir);	/* OK, normalize */
+				rayvalue(&sr);
+				scalecolor(sr.rcol, np->tspec);
+				multcolor(sr.rcol, np->mcolor);	/* modify */
+				addcolor(r->rcol, sr.rcol);
+				break;
+			}
+		}
 		ndims--;
 	}
 }